This is the Savox SB-2251SG Speed & Torque 6.0V Brushless Standard Size Steel Gear Digital Servo.

Features:

    Versatile balance of Speed & Torque in a Brushless Servo.
    Combines leading edge technology with super high 12 bit (4096) resolution and unique steel gears.
    Ideal for use in 6.0V applications.
    Brushless motor provides longer life and cooler operating temps.
    Extremely strong unique steel gears ensure long-life and durability.
    The full aluminum case design not only looks good but also allows for cooler and smoother operating temps.
    Our servos are totally green – from materials to production, these servos are environmentally friendly.
    Ideal for giant scale aircraft, monster truck, 1/8 scale.

Dimensions(mm): 40.3x20x37.2
Weight(g): 68.0
Speed(@6.0V sec/60): .085
Torque(@6.0V oz-in): 208
Gear: Unique Steel
Bearing: 2BB
Case: Full Aluminum
25 Tooth Spline
Frequency: 250-333
Pulse Rate Frequency: 1520